Decoupling of rotational and translational diffusion in supercooled colloidal fluids

Kazem V. Edmond, Mark T. Elsesser, Gary L. Hunter, David J. Pine, Eric R. Weeks

Research output: Contribution to journalArticlepeer-review

Abstract

Weuse confocal microscopy to directly observe 3D translational and rotational diffusion of tetrahedral clusters, which serve as tracers in colloidal supercooled fluids. We find that as the colloidal glass transition is approached, translational and rotational diffusion decouple from each other: Rotational diffusion remains inversely proportional to the growing viscosity whereas translational diffusion does not, decreasing by a much lesser extent. We quantify the rotational motion with two distinct methods, finding agreement between these methods, in contrast with recent simulation results. The decoupling coincides with the emergence of non-Gaussian displacement distributions for translation whereas rotational displacement distributions remain Gaussian. Ultimately, ourwork demonstrates that as the glass transition is approached, the sample can no longer be approximated as a continuum fluid when considering diffusion.

Original languageEnglish (US)
Pages (from-to)17891-17896
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number44
DOIs
StatePublished - Oct 30 2012

ASJC Scopus subject areas

  • General

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